Prevalence and incidence of anogenital warts and their association with HIV status and other factors in Kenyan men reporting high-risk sexual behavior, including men who have sex with men (2005-2013)

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Background: Human papillomavirus (HPV) causes a wide spectrum of disease ranging from warts to life-threatening cancers. Prevalence, incidence, and factors associated with anogenital warts in high-risk African men are largely unknown. Methods: Since 2005, men reporting high-risk sex behavior (having sex with men [MSM], transactional sex, recurrent sexually-transmitted infections [STI], serodiscordant or multiple sex partners) were followed at scheduled visits for collection of behavioral and clinical data (physical examination, HIV and STI testing). Visual inspection was used for detection of anogenital warts (AG) and genital ulcerations. Urethral and rectal samples were collected from symptomatic men to diagnose urethritis and proctitis. Logistic regression was used to identify associations between prevalent AG and predictors, adjusting for confounders. Adjusted incidence rates were calculated. A Cox regression analysis was performed to analyze predictors of incident AG, adjusting for confounders. Results: AG prevalence was 2.9% (95% CI: 2.0% - 4.0%). HIV was associated with increased AG prevalence (OR 5.43; 95% CI: 2.03 - 11.29; P <0.001). Follow-up time was 1,639 person-years (PY), with a median of 1.4 years, and a median number of visits of 6. AG incidence was 5.3 per 100 PY (95% CI: 4.3 - 6.5). HIV and being diagnosed with a genital syndrome were associated with an increased risk of acquiring AG (HR 1.66; 95% CI: 1.01 - 2.72; P 0.04 and HR 4.78; 95% CI: 3.03 - 7.56; P <0.001, respectively). Conclusions: We detected high prevalence and incidence of AG in a population of MSM and other high-risk men in Africa. AG prevalence is associated with HIV and that the risk of AG acquisition is associated with both having HIV and a genital syndrome. These findings motivate us to intensify our prevention efforts by expanding HPV vaccination in East Africa to include young men and by ensuring early diagnosis and treatment of STI (including HIV).